The majority of the railway type car coupling arrangements for joining adjacent ends of a pair of such cars are predominantly divided into either joining such railway cars in a substantially semi-permanent fashion such as drawbars or articulated couplings or joining in a temporary fashion, such as standard couplers.
Use of standard AAR (Association of American Railroads) couplers, generally type E or F, to join railroad cars is well known. Such couplers are designed to facilitate the connecting or disconnecting of individual railway cars allowing the cars to be readily combined to make a train or individually separated for loading or unloading.
The greater loads carried by modern railway cars necessitated maintenance of the close-butted relationships between various components to lessen the impact forces on railway cars and the coupling arrangements. As a result, closed buttoned relationships lead to development of slackless coupling arrangements primarily consisting of couplers and drawbars.
The primary advantage of the coupler generally used with a draft gear assembly is that it accommodates the longitudinal travel in both directions, as well as the vertical and lateral travel at the coupling as the railway cars progress along the track and, more particularly, enabling such cars to more easily negotiate the curved portion of the track which will be encountered during operation.
One type of such coupler arrangement is illustrated in U.S. Pat. No. 5,312,007 and includes a draft gear to absorb the load on a railroad car coupler in both the buff and draft directions of travel. The draft gear avoids shock-loading from sudden acceleration in the draft direction for couplers, while retaining the shock-loading or shock-absorbing capability of the assembly in the buff direction, especially for freight cars being humped.
Another type of coupler arrangement is illustrated in U.S. Pat. No. 4,480,758 and includes modification of the conventional yoke and draft gear enabling a larger draft gear to be positioned within the sill. A railway coupler arrangement includes a center sill having front and rear draft lugs within the sill. A draft gear housing is carried within the sill and is slideable between the front and rear draft lugs. A follower and plunger block is slideable in the center sill and is in engagement with one end of a draft gear. A yoke shank is provided with a butt engageable with the aforesaid follower and plunger block and is movable from a position where it engages forward wall means on the draft gear housing during draft loads to a position removed from the forward wall means where it forces the follower and plunger block into the draft gear during buff loads. Means are associated with the front draft lugs for engaging the follower and plunger block during draft loads to compress the draft gear.
A rotary coupler arrangement is also known in which the railway coupler shank includes a butt end which extends into the draft gear housing and is engageable with a cooperating spherical surface on the follower and plunger block. With an arrangement of this sort, the rotary coupler butt end is disposed aft of the front draft gear lugs on the sills and is positioned in a substantially horizontal plane for ease of coupling and uncoupling.
The primary disadvantage of the coupler and draft gear assembly is the weight of the draft gear. An additional disadvantage of the coupler and the draft gear assembly is the high unit cost of the draft gear due to the complexity of the design and a requirement for a significant number of components.
Lately, slackless drawbar assemblies have substantially eliminated the need for a relatively expensive draft gear assembly. Furthermore, these slackless drawbar assemblies have generally resulted in a desirable overall net decrease in the empty weight of such railway freight cars as well as an overall decrease in unit cost. Decrease in empty weight allows either reduced fuel costs when such railway freight cars are being hauled or an increase in weight of the net load being hauled.
One type of such slackless drawbar is taught in U.S. Pat. No. 5,547,089 and includes a female connection member with one end engaging an end of a car body center sill and another end extending outwardly from the center sill end and a male connection member having a first end movably disposed in such cavity and a second end for coupling to a male connection member of the adjacent railway vehicle. An aperture is formed through such male connection member first end. A cavity formed in such other end of the female connection member defined by inner surfaces of the back wall, top wall and pair of side walls having openings and open at a bottom and outer end thereof. A portion of a spherical shaped ball member having a pair of shaft members extending from outer surfaces is disposed in such aperture. A portion of each shaft member is disposed in respective side wall openings. Each shaft member has a flat surface formed thereon. A race has a portion thereof disposed in such aperture and is secured to such male connection member. The race inner surface is disposed around the spherical member.
Another type of such slackless coupling arrangement is taught in U.S. Pat. No. 6,176,379 and includes a ball and race assembly having a one piece race assembly integrally formed onto the ball. The ball and race assembly includes a ball member having a spherical shape with a predetermined diameter and a one piece race member which is formed integrally with at least a portion of the ball member in a manner so as to enable rotational movement of the ball member with respect to the race member. The race member is a filament wound composite type material which is wound about the ball member so as to produce an outer surface which is capable of being positioned within an appropriate holding device. The outer surface of the race member has a shape which is capable of being placed within an aperture of a male connection member in a railway coupling device so as to enable rotational movement of the male connection member with respect to a car connection member of the coupling device.
The teachings of U.S. Pat. Nos. 5,547,089 and 6,176,379 are incorporated in this application by reference thereto.